Inhibition of histaminergic receptors in rat jejunum by Indacrinone

Indacrinone is a loop diuretic which also has uricosuric, kaliuretic, saliuretic and natriuretic effects. Since it has been reported that this drug has several actions in different organs, we decided to evaluate its mechanism of action on the rat jejunum smooth muscle. After preparation of the tissues, different concentrations of indacrinone were applied. Doses of 8.2×10^-6 M, 2.7×10^-5 M, 8.2×10^-5 M and 2.7×10^-4 M were all effective in a dose dependent manner to relax the muscle. Increase in the drug concentration resulted in much faster reduction in twitch amplitude. The jejunum is innervated by adernergic, cholinergic, serotonergic and histaminergic systems. To find the mechanism of action of indacrinone in rat jejunum, experiments were conducted by appropriate receptor agonists and antagonists of the above systems. There was a marked increase in muscle contraction tone and ampliture by the use of histamine, while indacrinone prevented the increase induced by histamine. It was concluded that indacrinone may be a competitive antagonist for histamin receptors in rat jejunum muscle